Unless otherwise configured, the client libraries use Application Default Credentials to authenticate with Google Cloud Services. While this works for most applications, in some cases you may need to override this default. You can do so by providing the UnifiedCredentialsOption The following example shows how to explicitly load a service account key file:
[](std::string const& keyfile) {
auto is = std::ifstream(keyfile);
is.exceptions(std::ios::badbit); // Minimal error handling in examples
auto contents = std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
auto options =
google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
google::cloud::MakeServiceAccountCredentials(contents));
return google::cloud::documentai_v1::DocumentProcessorServiceClient(
google::cloud::documentai_v1::MakeDocumentProcessorServiceConnection(
options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-14 UTC."],[[["This webpage provides a comprehensive list of Document AI C++ client library versions, ranging from version 2.37.0-rc (latest) down to 2.11.0, each with a corresponding link."],["The content explains how to override the default authentication credentials by using the `UnifiedCredentialsOption`, allowing for the explicit loading of a service account key file."],["The default authentication method for the client libraries utilizes Application Default Credentials; however this can be adjusted for specific applications."],["The example code provided demonstrates loading a service account key file and includes a link to best practices for managing service account keys for more information."],["The \"See Also\" section directs users to \"Authentication Components\" for details on creating `google::cloud::Credentials` objects."]]],[]]